30 St Mary Axe, also known as the Gherkin and the Swiss Re Building, is a skyscraper in London’s main financial district. Completed in December 2003 it is 180 meters (591 ft) tall, with 40 floors.
The building uses energy-saving methods which allow it to use half the power a similar tower would typically consume. Gaps in each floor create six shafts that serve as a natural ventilation system for the entire building .The shafts create a giant double glazing effect; air is sandwiched between two layers of glazing and insulates the office space inside.
The shafts pull warm air out of the building during the summer and warm the building in the winter using passive solar heating. The shafts also allow sunlight to pass through the building making more pleasant work environment and reducing lighting costs.
In December 2005, the building was voted the most admired new building in the world, in a survey of the world’s largest firms of architects.